Hi cbdaz
A couple of things you can try. You will need to have Trainz open when you do this.
The first is to right click on the speaker icon on your taskbar, then click on 'open volume mixer'.
In the volume mixer, scroll across till you find TRS19. Please make sure the volume is set to a suitable level here, and that the sound is not muted.
If this does not resolve the issue, then please try going into TRS19 and then click on the 'system menu' button (3 horizontal bars) at the top left of the screen. Now click on 'settings', then click on 'sound settings'. Please ensure that the volume here is set to a suitable level.
Regards